Compact 3D direction finder

Abstract

An apparatus that includes two non-coinciding arrangements disposed in an two axes Cartesian coordinate system such that each arrangement having a non-zero projection on a respective axis from among the two axes. Each one of the arrangements includes a pair of oppositely directed, spaced apart, co-axial radiating-capable elements, each of the elements being hollow with internal space, and being slotted throughout its entire extent. A first circuitry coupled to the arrangement and being configured to sense an electric field projection along the axis and to convey it to a first feeding terminal. A second circuitry coupled to a slot of the arrangement and being configured to sense a magnetic field's projection along said axis and to convey it to a first feeding terminal.

The invention claimed is: 
     
       1. An apparatus, comprising:
 at least two non-coinciding arrangements disposed in an at least two axes Cartesian coordinate system such that each arrangement having a non-zero projection on a respective axis from among said at least two axes; each one of said arrangements includes at least one pair of oppositely directed, spaced apart, co-axial radiating-capable elements, each of said elements being hollow with internal space, and being slotted throughout its entire extent; a first circuitry coupled to said arrangement and being configured to sense an electric field projection along said axis and to convey it to a first feeding terminal; 
 a second circuitry coupled to at least one slot of said arrangement configured to sense a magnetic field's projection along said axis and to convey it to a first feeding terminal. 
 
     
     
       2. The apparatus according to  claim 1 , wherein each arrangement has a first longitudinal dimension and is capable of sensing a magnetic field projection along said axis and an electric field projection along said axis in a decade frequency band where the said first longitudinal dimension is smaller than λ MIN /10 and where λ MIN  corresponds to the highest frequency of said frequency band. 
     
     
       3. The antenna according to  claim 1 , wherein said first circuitry includes passive elements. 
     
     
       4. The apparatus according to  claim 3  wherein said passive elements include a transformer. 
     
     
       5. The apparatus according to  claim 1 , wherein said first circuitry includes active elements. 
     
     
       6. The apparatus according to  claim 5 , wherein said active elements include a differential amplifier. 
     
     
       7. The apparatus according to  claim 1 , wherein each element in any of said arrangements being a hollow cylinder slotted throughout its entire longitudinal extent. 
     
     
       8. The apparatus according to  claim 1 , wherein each element being a hollow polygon slotted throughout its entire longitudinal extent. 
     
     
       9. The apparatus according to  claim 1  wherein said first circuitry is coupled to an arrangement in a gap between the elements. 
     
     
       10. The apparatus according to  claim 1 , wherein said second circuitry includes passive elements. 
     
     
       11. The apparatus according to  claim 10  wherein said passive elements include a transformer. 
     
     
       12. The apparatus according to  claim 1 , wherein said second circuitry includes active elements. 
     
     
       13. The apparatus according to  claim 12 , wherein said active elements include a differential amplifier. 
     
     
       14. The apparatus according to  claim 10 , wherein said passive elements are coupled to an arrangement by a galvanic combination of one slot center, while all other of said slots are loaded for symmetry. 
     
     
       15. The apparatus according to  claim 10 , wherein said passive elements are coupled to an arrangement by a galvanic combination to each slot center of said slots. 
     
     
       16. The apparatus according to  claim 10 , wherein said passive elements include at least one magnetic element accommodated within the spaces of said at least one pair of elements and extending along a major portion of the elements' longitudinal extent. 
     
     
       17. The apparatus according to  claim 16 , wherein said magnetic element includes a multi-turn loop over a ferrite rod. 
     
     
       18. The apparatus according to  claim 16 , wherein said element is coupled to said slots for sensing the accumulated magnetic field projection. 
     
     
       19. The apparatus according to  claim 1 , wherein at least one of said arrangements having a non-zero projection on an additional axis from among said at least two axes. 
     
     
       20. The apparatus according to  claim 1 , wherein at least one of said arrangements having additional at least one non-zero projection on additional at least one axis from among said at least two axes. 
     
     
       21. The apparatus according to  claim 1 , wherein said arrangements are disposed perpendicularly to each other. 
     
     
       22. The apparatus according to  claim 21 , wherein said arrangements are disposed along said at least two axes. 
     
     
       23. The apparatus according to  claim 1 , wherein each one of said arrangements is spaced apart relative to the origin of said Cartesian system at a respective distance that falls in the range of 0 to λ MIN , where λ MIN  corresponds to the highest frequency of a decade frequency band. 
     
     
       24. The apparatus according to  claim 1 , for resolving the direction of arrival of an electro-magnetic (EM) wavefront. 
     
     
       25. The apparatus according to  claim 1 , for resolving the polarization of an electro-magnetic (EM) wavefront. 
     
     
       26. The apparatus according to  claim 1 , comprising three non-coinciding arrangements disposed in three axes Cartesian coordinate system such that each arrangement having a non-zero projection on a respective axis from among said three axes. 
     
     
       27. The apparatus according to  claim 1 , comprising two non-coinciding arrangements disposed in two axes Cartesian coordinate system such that each arrangement having a non-zero projection on a respective axis from among said two axes. 
     
     
       28. An apparatus comprising:
 at least two mutually perpendicular antennae for measuring electric and magnetic field projections along at least two distinct axes; 
 each antenna from among said antennae includes: 
 (a) an arrangement that includes at least one pair of oppositely directed, spaced apart, co-axial radiating-capable elements, each of said elements being hollow with internal space, and being slotted throughout its entire extent; a first circuitry coupled to said arrangement and being configured to sense an electric field projection along said axis and to convey it to a first feeding terminal; 
 (b) a second circuitry coupled to at least one slot of said arrangement configured to sense a magnetic field's projection along said axis and to convey it to a first feeding terminal; 
 (c) the antennae are coupled to at least one receiver for measuring said sensed electric and magnetic projections in each one of said axes. 
 
     
     
       29. The apparatus according to  claim 28  comprising three mutually perpendicular antennae for measuring electric and magnetic field projections along three distinct axes. 
     
     
       30. The apparatus according to  claim 28  comprising two mutually perpendiculiar antennae for measuring electric and magnetic field projections along two distinct axes. 
     
     
       31. A system that includes at least one pair of apparatuses, each apparatus being constructed in accordance with  claim 1 ; each pair of said pairs of apparatuses is coupled substantially symmetrically over a substantially symmetric object having at least one symmetric plan in a manner that substantially maintains an original symmetric plan of said plans when considering a consolidated structure that is composed of the object and the pair of apparatuses. 
     
     
       32. The system of  claim 31  wherein the electric field projection measurement of each arrangement of a first apparatus of said pair is combined with the electric field projection measurement of a corresponding arrangement of the second apparatus of said pair, giving rise to combined electric field projection measurements respectively; and wherein the magnetic field projection measurement of each arrangement of the first apparatus is combined with the magnetic field projection measurement of a corresponding arrangement of the second apparatus, giving rise to combined magnetic field projection measurements respectively. 
     
     
       33. A method for determining direction of arrival of an electro-magnetic (EM) wavefront, comprising
 (i) providing at least two non-coinciding arrangements disposed in at least two axes Cartesian coordinate system such that each arrangement having a non-zero projection on a respective axis from among said at least two axes; each one of said arrangements includes at least one pair of oppositely directed, spaced apart, co-axial radiating-capable elements, each of said elements being hollow with internal space, and being slotted throughout its entire extent; a first circuitry coupled to said arrangement and a second circuitry coupled to at least one slot of said arrangement 
 (ii) utilizing said first circuitry for sensing an electric field projection along said axis and to convey it to a first feeding terminal; 
 (iii) utilizing said second circuitry for sensing a magnetic field's projection along said axis and to convey it to a first feeding terminal; and 
 (iv) utilizing said at least two arrangements for resolving the direction of arrival of an electro-magnetic (EM) wavefront. 
 
     
     
       34. The method according to  claim 33  comprising:
 (i) providing three non-coinciding arrangements disposed in three axes Cartesian coordinate system such that each arrangement having a non-zero projection on a respective axis from among said three axes; each one of said arrangements includes at least one pair of oppositely directed, spaced apart, co-axial radiating-capable elements, each of said elements being hollow with internal space, and being slotted throughout its entire extent; a first circuitry coupled to said arrangement and a second circuitry coupled to at east one slot of said arrangement; 
 (ii) utilizing said first circuitry for sensing an electric field projection along said axis and to convey it to a first feeding terminal; 
 (iii) utilizing said second circuitry for sensing a magnetic field's projection along said axis and to convey it to a first feeding termninal; and 
 (iv) utilizing said three arrangements for resolving the direction of arrival of an electro-magnetic (EM) wavefront. 
 
     
     
       35. The method according to  claim 33  comprising:
 (i) providing two non-coinciding arrangements disposed in two axes Cartesian coordinate system such that each arrangement having a non-zero projection on a respective axis from among said two axes; each one of said arrangements includes at least one pair of oppositely directed, spaced apart, co-axial radiating-capable elements, each of said elements being hollow with internal space, and being slotted throughout its entire extent; a first circuitry coupled to said arrangement and a second circuitry coupled to at least one slot of said arrangement; 
 (ii) utilizing said first circuitry for sensing an electric field projection along said axis and to convey it to a first feeding terminal; 
 (iii) utilizing said second circuitry for sensing a magnetic field's projection along said axis and to convey it to a first feeding terminal; and 
 (iv) utilizing said two arrangements for resolving the direction of arrival of an electro-magnetic (EM) wavefront.